1. Field of the Invention
The present invention relates to a sewing apparatus so designed to effect sewing in a curved or sinuous fashion.
2. Description of the Prior Art
In the past, and in general, sewing one cloth to another one in a curved or sinuous fashion has not, in practice, been accomplished by automatic means because of technical difficulties remaining in such an intricate sewing process. In most cases, an operator has to manually manipulate the separately cut base cloths for curved or sinuous sewing purposes, using a conventional sewing machine. Therefore, an accumulation of skill or expertise has been required to achieve this sewing technique, resulting in obstacles to high efficient and rapid sewing processes of the type required to keep abreast with the recent automation-oriented tendency.
The inventor of the present invention previously proposed providing a sewing apparatus to realize the automatization of sewing a curved seam. According to this first invention, a stationary plate is fixed on the table of a sewing machine and a movable plate is slidably mounted on the stationary plate. The stationary plate has a guide means projected thereon and a curved, or sinuous, elongated groove formed thereon. On the other hand, the movable plate is formed with a peripheral edge which conforms to a given curved sewing path along which a cloth or base material is sewn from the start point through a generally 90-degree-angle curvature to the end point. This movable plate has a curved guide hole similar in shape to the foregoing sewing path and a dependent guide means projected from the underside of the movable plate. The sinuous elongated groove of the stationary plate is of a configuration corresponding to a track in which the movable plate has to be moved for allowing the cloth or base material to be sewn in such curvature. The guide means of the stationary plate is slidably inserted through the curved guide hole of the movable plate, and the guide means of the movable plate is slidably fitted in the sinuous elongated groove of the stationary plate.
Accordingly, the cloth secured on the movable plate is sewn in a curved manner from the combination of the curved guide hole of the movable plate and sinuous elongated groove of the stationary plate, by virtue of the fact that the curved guide hole serves to guide the movable plate along this generally 90-degree curvature and the sinuous elongated groove serves to cause the movable plate to move along the curved guide hole. Hence, the cloth is automatically sewn in a predetermined curved manner.
But, the above-described first invention has been limited to curved sewing, and sewing to provide a generally sine-shaped or -like sewing pattern has not been made possible with that prior art. The reason is that the two guide means respectively associated with the stationary and movable plates are moved in a mutually co-acting relation for the sole purpose of sewing the cloth in a generally 90-degree-angle curvature. No effective automatic sewing apparatus has yet been proposed for automatically sewing sine-shaped sewing patterns.